Research communicaƟ ons by NF-POGO alumni Vo Xuan Mai and Le Nhu Hau

Vo Xuan Mai A and Le Nhu Hau B

Researcher A and Head of Research B at the Department of Organic Material from the Sea Resources, Nhatrang InsƟ tute of Technology Research and ApplicaƟ on, Vietnam Wikipage: hƩ p://www.nf-pogo-alumni. org/~Mai+Vo+Xuan

Methods and materials

1Study sites

Area of research covers the coordinate rangi from 109° 4’ 9.84 “ to 109° 9’ 38.88” E and 15° 2 23.64” to 15° 21’ 26.28” N at Ly Son island district ( An Binh, An Vinh and An Hai). and underwater fi lming (Olympus 10.x), quanƟ -

An assessment for distribuƟ on status of the Sargassum seaweed resources in Ly Son Island district, Quang Ngai province, Vietnam

IntroducƟ on:

Ly Son island district is located in the Northeast of Quang Ngai: two islands and three communes. Lon Island (Ly Son island, Lao Re) has two communes, An Hai and An Vinh; Be Island (Cu Lao Bo Bai) has An Binh commune. They are approximately 15 nauƟ cal miles from the mainland (Sa Ky port). The structure of coastal island terrain is surrounded with the alterable communiƟ es of coral, seaweed and seagrass. The stretch slope Ɵ de from 1 - 2 km creates diverse and abundant Ɵ dal coastal ecosystems. Therefore, research scienƟ sts are interested in this area from many diff erent perspecƟ ves, such as archeology, depth topography, seaweed resource allocaƟ on and resource exploitaƟ on of special seafood products. Sargassum seaweed has an important role in coastal ecosystems, for example by providing inhabitaƟ on and hiding grounds for marine animals. Carpet of Sargassum seaweed form the hiding and reproducƟ ve place for the larval stages of species such as shrimp, crab, fi sh, squid, scallops, etc. Sargassum seaweed is a raw product used in many areas of industry: food processing, cosmeƟ cs, agricultural ferƟ lizers, etc. Sargassum has a high biological acƟ vity and has been found to enhance the immune system, has anƟ -tumor, anƟ -cancer and anƟ viral properƟ es, lowers cholesterol, reduces high blood pressure, prevents blood clots, and reduces stomach ulcers. Assessing the resource area of Sargassum in Ly Son Island by tradiƟ onal methods is Ɵ me consuming and expensive. Therefore, remote sensing and GIS techniques are used by domesƟ c researchers as a tool to assess the distribuƟ on of seagrass, seaweed and coral coastal ecosystems in

2DescripƟ on of material

- GPS: Garmin 76CS (U.S.), digital cameras, Vietnam (Thanh et al., 1998; Son et al., 2004; Mai et al., 2010).

taƟ ve framework (0.5 x 0.5 m) and sample bag. - The analysis soŌ ware and image processing satellite data - GIS: ENVI 4.5, Map-Info 9.0. - Base map and code 67 391-I scale: 1/50.000, Google Earth panchromaƟ c image scale: 1:10,000 (2013). -Two Landsat scene 8 (15m resoluƟ on), taken April 6, 2013 (number C81240492013095LGN0 1 Two-AVNIR2 scene ALOS images (10 m resoluƟo taken on June 20, 2011 (number ALAV2A1280833 O1B2R_U. - There are 60 seaweed samples collected from 2 0 study area (Figure 1). Reference data according to 4/2013, 5/2013 and 6/2013 in Ly Son Island. The b eters of the coverage and classifi ed biomass of fre cies composiƟ on were also assessed at the study s analysis was performed in the laboratory.

- Morphology and scienƟfi c names of the Sargass classifi ed according to Ho, 1969; Dinh et al., 1993 erage and seaweed biomass is calculated by the (1970) and Margarita (2003).

To overcome these limitaƟ ons, the assessment of the distribuƟ on, density and yield of Sargassum carpet using remote sensing technology applicaƟ ons and GIS methods will be presented in this arƟ cle.

Results and Discussion: 1 DistribuƟ on area, biomass, yield and species of Sargassum in Ly Son Island

Sargassum develops in Ly Son Island district on solid substrates such as coral reefs. Sargassum development starts from March to April. The distribuƟ on area, biomass, yield, and species composiƟ on are shown in Table 1. The total distributed area of Sargassum is 246 ha, Sargassum yield of Ly Son Island (including the Lon island and Be island) is 4,225 tons (fresh weight).

2 Analysis of Sargassum carpet distribuƟ

From the document resource with Lands chromaƟ c image types and surveyed dat a of the invesƟ gaƟ on and verifi caƟ on locaƟ has been applied according to the analysis basis of the key locaƟ ons separated spect r mum Likelihood (Edmund et al., 2000, N content from the cited theme “Remote sen resources Sargassum in Ly Son island - Qu

o the survey trip biological paramsh seaweed spesite. The detailed

um seaweed are ; Dai, 1997. Covmethod of Saito

3Field survey method to assess the status of seaweed

Survey transect methods of invesƟ gaƟ on normaƟ ve seaweed of 20 secƟ ons is based on State CommiƩ ee for ScienƟfi c (1981). The quadrant is randomly selected perpendicular to the shore from where algae grow best near shore to widen the lowest development. All sampling posiƟ ons, photos, fi lms, and physical parameters were gathered. From the survey coordinates, 60 samples from the 20 selected cross secƟ ons, record the type of substrate (sand, rock, coral), depth, seaweed and seagrass. The fundamental point of the invesƟ gaƟ on supports the construcƟ on of the key points of interpretaƟ on of the remote sensing images areas of seaweed distribuƟ on and isolates them from other objects. The calculaƟ on of the index of the depth invariant band pairs (bands) is required in the image interpretaƟ on. The method of Saito and Atobe (1970) is used as an assessment of seaweed area coverage. The total count of seaweed and weight for each bag is used to calculate the density and amounts of fresh material g.m -2 . The Sargassum seaweed yield are calculated by the formula [B= averaged biomass X area distribuƟ on]. 0 secƟ ons of the

4The method of remote sensing image interpretaƟ on and GIS in mapping Sargassum carpet

The corrected maps together with the coordinates GIS system build the basic layer of informaƟ on vectors (boƩ om topography, bathymetry points, seaweed sample, etc). Data was then transferred from the survey point maps into GIS systems. A database of the survey is included in the model displayed in the GIS system, in order to verify the interpretaƟ on of the parameters for seaweed distribuƟ on area.

The process of interpretaƟ on of seaweed distribuƟ on is based on the principle of the method of calculaƟ ng the index depth invariant based on Edmund et al., 2000; Nyoman et al., 2003; Hau et al., 2009). GIS technology is used in the analysis, and data processing techniques are used to overlay informaƟ on on the current status of the distribuƟ on of Sargassum carpet for the construcƟ on of themaƟ c maps.

on status from remote sensing images

at, ALOS-AVNIR2 Google Earth and pana from the locaƟ ons, line staƟ ons, status ons. Remote sensing and GIS technology process and image interpretaƟ on. On the ral band combinaƟ ons with isolated MaxiNyoman et al., 2003). Detailed reference nsing image interpretaƟ on locate, coastal uang Ngai province”, “Status of species”. Status of distribuƟ on results, species composiƟ on, area, carpets Sargassum yield in the island district of Ly Son expressed in Table 1. Conclusion: On the basis of fi eld surveys, the collected sample has been classifi ed. There are 13 species of Sargassum populaƟ on. The area of Sargassum distribuƟ on of Ly Son Island district is esƟ mated to be 246 ha with the fresh yield 4,225 tons/year. In this area, Sargassum grows on dead reef plaƞ orms and forms low biomass blooms in April every year.

For references, please contact the authors